#include<stdio.h>
#include<iostream.h>

#define TMAX 1000000

int n,t,i, x,y;

long c,minim[TMAX+1];

long long sol;

int main()
{
  freopen("gardieni.in","r",stdin);
  freopen("gardieni.out","w",stdout);

  scanf("%d %d",&n,&t);

  memset( minim,1,sizeof(minim) );

  for(i=1; i<=n; i++)
  {
    scanf("%d %d %ld", &x, &y, &c);

    while( x <= y)
      {
       if( minim[x] > c)
       minim[x] = c;

       x++;    }

  }


  for(i=1; i<=t; i++)  sol+=minim[i];


  printf("%lld\n",sol); return 0;}